Conventionally, display devices which include organic EL elements have been developed. In such display devices, organic EL elements are caused to emit light upon voltage being applied between anodes and cathodes of the organic EL elements. A power source for applying a cathode voltage via a line is connected to the cathode of the organic EL element. Here, in the line extending from the power source to the cathode, contact resistance is present at a contact portion of a terminal, for example, where two conductors are brought into contact. If there is a poor connection at the contact portion, the contact resistance at the contact portion increases, and the desired potential cannot be applied to the cathode. Accordingly, the organic EL element cannot be caused to emit light at the desired luminance. In addition, depending on the pixel driving method, if the contact resistance is high at the contact portion, the contact resistance may cause poor image quality such as crosstalk.
In view of the above, a display device, which can measure contact resistance present between a power source and a display panel, has been proposed (for example, see Patent Literature (PTL) 1). The display device disclosed in PTL 1 causes the organic EL element to emit light at a desired luminance by measuring contact resistance present at a line extending from the power source to the display panel and applying a potential according to the contact resistance.